Heat treating oven



1932. c. A. HERBST I HEAT TREATING OVEN Filed Feb. 18, 1951 ZZZ/67215;!aareizce Qflerbsi Patented Dec. 27, 1932 UNITED STATES PATENT OFFICECLARENCE A. HERBST, OF CHICAGO, ILLINOIS, .ASSIGNOR TO ECONOMY FUSE ANDMAN I FACTUBING 00., OF CHICAGO, ILLINOIS, .A CORPORATION OF NEW YORKHEAT TREATING OVEN Application filed February 18, 1931.

This invention relates to improvements in a heat-treating oven which isespecially applicable for heat treating cold-molded products.

It is an object of the invention to provide an oven which may be heatedby combustion, such as by gas burners and into which material may becharged on trays and racks and to provide means for circulating theheated air within the oven and to so design the apparatus thatsubstantially uniform tempera ture conditions may be maintained for allthe material being heat-treated.

It is further an object of the invention to provide a series of radiatortubes on each side of the oven which is separated from the trays andracks of material by heat-radiating shields and to use a fan at one endof the oven which produces a circulation of the air so as to draw theair past the material being treated and direct the air to flow betweenthe walls of the oven and the shields thereby passing over the radiatortubes and to additionally provide for uniform temperature conditionsthroughout the length of the oven by admitting a portion or portions ofthe heated air from the space between the shields and the walls to theinterior of the oven in contact with the material treated while theremainder of heated air passes to the extreme end of the oven.

Further objects and advantages of the invention will be more readilyapparent from the description taken in connection with the attacheddrawing, in which Figure 1 is a horizontal section taken through theoven illustrating the racks and trays diagrammatically;

FigureQ is a vertical longitudinal section of the oven taken on theplane indicated 22 in Figure 1, and

Figure 3 is a vertical transverse section of the oven showing theburners and flue connections.

Serial No. 516,666.

in the usual manner such as bymagnesia I opposite end of the ovenprotrudes thereinto and carries a circulating fan 13 while the shaft isdriven by an exterior pulley 14. A

plurality of racks 15, which carry a plurality of: trays, for thematerial treated may be charged into the oven as indicated in Figures 1and 3 where there are shown four racks extending throughout the lengthof the oven. Heat radiating shields 1616 extend from top to bottom ofthe oven but the ends thereof are spaced from the ends ofthe oven. Aclosed combustion chamber 17 is provided at each side of thebottom ofthe oven into which extend a pair of burner tubes 1818. The gases burnedin the combustion chambers are directed to flow through a series ofradiator tubes 19 which extend vertically between the lower combustionchambers and a pair of closed headers 2020 at the upper portion of theoven. The consumed gases are directed through flues 21-21 to a stack 22.

It will, therefore, be understood that all the air within the oven whichcomes in contact with the material treated is heated by radiation fromthe radiator tubes. The fan 13 is driven in such direction that the airwithin the oven is drawn from the end of the oven which carries thedoors towards the fan, and the air which passes the fan is directedlaterally to flow forward towards the doors of the oven in the conduitsformed be tween the walls and the shields thereby coming in contact withthe heated radiator tubes. The arrows in Figure 1 illustrate the flow ofair.

An oven of the type disclosed herein is especially adaptable for use inheat-treating cold-molded products. Such products are molded to theproper shape and the-n charged into the oven and heat is applied with agradually rising temperature for a period of several hours, during whichthe cold-molded products are absorbing heat. lVhen the criticaltemperature is reached, a reaction occurs and the material istransformed into ahard and infusible product. During the reaction heatis being given out from the material since the reaction is exothermic.highly desirable that all of the material be brought to the criticaltemperature at substantially the same time.

It will be obvious that if asingle fan is used to draw the air from oneend of the oven to the other end and then pass over the radiatortubesback to the first end of the oven that the last rack, which is chargedinto the oven, will be subjected to' a greater tempera;

ture than the first rack which is closest to the fan since thetemperature will diminish towards the fan, due to the absorption ofheat. It is, therefore, necessary to add additional heat units atsuccessive points along the oven so that the material which is nearestthe fan will receive the same amount of heatas the material nearest thedoors. 1

One manner of obtaining this desirable result is illustrated in .Figure1 in which I have showna pair of bafiies 23-23 adjacent openings 2al24in the shields at the middle portion of the oven. The battles are soarranged that a portion of the air flowing towards the front endof theoven is caused to flow hrough the openings 24 and join the current ofair flowing towards the fan. The additional air which flows through theopenings will provide sufiicient heat units to maintain a more uniformtemperature at the opposite ends of the oven.

It is also desirable to have the combustion chamber insulated at thebottom of the oven, such as by insulating material, indicated 25 inFigure 3, so that the lower trays of material will not receive a greaterproportion of heat than the uppertrays due to direct radiation from thecombustion chamber through the shields. e

My invention is particularly adapted to be -used in connection with anoven in which the dimension in the'direction of the current ofcirculating air is substantially greater than the dimension across thecurrent of air, but various changes and modifications may be resorted towithout departing from the spirit of the invention as expressed in theappended claims. The important feature of the invention is that in anoven of the type mentioned, I provide for uniform temperature conditionsthroughout the oven by the design of the radiating shields and openingsat certain-points of the oven to compensate for the heat absorbed by thefirst material which the air passes over.

It is, therefore,

shieldsto compensate for the absorption of heatby the-material treated.v y

2. A heat treating oven comprising a closed. chamber, a pair of conduitsfor the circulation of air on the opposite sides of the chamber, meansfor'dirculating the air within the chamber by drawing the air from oneend of the chamber to the other between the side conduits during whichthe air passes over the material treated and then forcing the air toflow longitudinally in the opposite direction through said conduits,means for heating the air as it flows through the side conduits andmeans for admitting portions of the heated air from the conduits intothe space therebetween at points intermediate the ends of the oven. I

i v A. heat treating oven comprising a closed chamber, a pair of heatradiating shields at the sidesof the chamber spaced from the walls todefine circulating conduits for the air within the chamber, a fan withinthe chamber at one end thereof operative to draw the air towardsthe fanfrom the opposite-end of the chamber between the shields and todirecttheair to flow'back towards the opposite end of the oven by flowingthrough Us thecirculating conduits and means for heating the air as itflows through the circulating conduits. said conduits having openings atpoints intermediate the ends of the chamber whereby some of the air isdrawn into the central portion of the chamber before it reaches the endof the chamber toward which it is flowing.

4. A heat treating oven comprising a closed chamber having side and endwalls, a pair of longitudinal combustion chambers along'the sides of thechamber adjacent the bottom thereof, a pair of longitudinal headers atthe upper portion'of the oven, radiator tubes joining the combustionchambers 3 to the headers, a pair'of heat radiating shields within thechamber on the inner side of the radiator tubes. means for circulatingthe air in the chamber by drawing the air towards the end of the chamberbetween the shields and directing the air to flow back towards the firstend ofthechamber in contact [with the radiator tubes, said shieldshaving openings intermediate the ends of the chamber andbafl'lesadjacent said openings for directing some of the air back to the centralportion of the chamber before it reaches the end of the chamber towardwhich it is flow A heat-treating oven comprising a closed air chamberhaving a doorway at one end thereof, racks for the material to beheattreated adapted to be moved into said chamber through said doorway,means for closing said doorway, a pair of air circulating passagewaysextending along the opposite sides of the chamber within the interiorthereof open at their ends for communication through the central portionof the chamber, an air circulating fan centrally positioned adjacent theend of the chamber opposite the doorway, said fan being adapted to drawthe air longitudinally of the chamber past the material to beheat-treated and to force the air to flow longitudinally in the oppositedirection through said passageways, means for heating the airsubstantially throughout the entire length of said passageways as theair fiows therethrough, the inner walls of said passageways havingvertical slotted openings extending substantially throughout the entireheight thereof, placing the passageways in communication with thecentral portion of the chamber at points intermediate the ends of thechamber and vertical bafiles extending from the edges of said slotsfarthest from the fan and directed inwardly with respect to said airpassageways whereby predetermined portions of air flowing through saidpassageways are caused to be directed into the central portion of saidchamber to maintain a more even temperature condition of the air flowingpast the material to be heat-treated.

6. A heat-treating oven comprising a closed air chamber having a lengthmaterially greater than the width thereof, a doorway at one end of saidchamber, a plurality of racks for supporting the material to beheat-treated adapted to be moved into said chamber through said doorwayand to remain station ary within said chamber while the material isbeing heat-treated, means for closing said doorway, apair of aircirculating passageways extending along the inner side walls of saidchamber substantially throughout the entire length thereof, saidpassageways being open at their opposite ends for communication throughthe central portion of said chamber adjacent the ends thereof, an aircirculating fan centrally positioned adjacent the end of said chamberopposite said doorway adapted to draw the air longitudinally of saidchamber past the material to be heattreated and to direct the air toflow longitudinally in the opposite direction through said passagewaysalong the side of said chamber, means for progressively heating the airas it flows through each of said passageways substantially throughoutthe entire length thereof, the inner walls of said passageways havof airflowing

